Vehicle rear monitoring system

ABSTRACT

A vehicle rear monitoring system ( 1 ) includes a camera ( 40 ) that captures an image of an area to a rear of a vehicle, and a processing unit ( 10 ) that processes the image captured by the camera. The processing unit ( 10 ) creates a first vehicle rear image that is displayed in a first display area ( 22 A) that is a portion of a display area of a display device, when traveling forward, and creates a second vehicle rear image that is displayed in a second display area ( 22 ) that is within the display area of the display device and that is an area that includes the first display area and is larger than the first display area, when traveling backward.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a vehicle rear monitoring system provided witha camera for capturing an image of an area to the rear of a vehicle.

2. Description of Related Art

Japanese Patent Application Publication No. 2009-166624 (JP 2009-166624A), for example, describes a vehicle rear monitoring system thatextracts, as a display image, an image of a relatively narrow area froman image of an area to the rear of a vehicle captured by a rear camerawhile the vehicle is traveling forward, enlarges this display image tothe size comparable to an inner rearview mirror, and displays thisenlarged display image on a display.

However, when the display area of the display apparatus that displaysthe vehicle rear image is fixed, there may be cases in which the size ofthe display of the vehicle rear image is not appropriate depending onthe traveling situation. For example, if the display of the vehicle rearimage is too large, it may be annoying to a driver when travelingforward, or if the display of the vehicle rear image is too small, theimage may be difficult to visually recognize when the vehicle istraveling backward.

SUMMARY OF THE INVENTION

Thus, the invention provides a vehicle rear monitoring system capable ofdisplaying an image in an optimal display area when a vehicle istraveling forward and in an optimal display area when the vehicle istraveling backward.

One aspect of the invention relates to a vehicle rear monitoring systemthat includes a camera that captures an image of an area to a rear of avehicle and outputs the captured image; a processing unit that processesthe captured image, and creates a vehicle rear image; a display devicethat displays the vehicle rear image; and a traveling directiondetecting device that detects a traveling direction of the vehicle andnotifies the processing unit of the detected traveling direction. Theprocessing unit creates a first vehicle rear image that is the vehiclerear image that is displayed in a first display area that is a portionof a display area of the display device, when the traveling direction isforward, and creates a second vehicle rear image that is the vehiclerear image that is displayed in a second display area that is within thedisplay area of the display device and that is an area that includes thefirst display area and is larger than the first display area, when thetraveling direction is backward.

According to the invention, a vehicle rear monitoring system capable ofdisplaying a vehicle rear image in an optimal display area when avehicle is traveling forward and in an optimal display area when thevehicle is traveling backward is able to be obtained.

BRIEF DESCRIPTION OF THE DRAWINGS

Features, advantages, and technical and industrial significance ofexemplary embodiments of the invention will be described below withreference to the accompanying drawings, in which like numerals denotelike elements, and wherein:

FIG. 1 is a view of an example of the basic structure of a vehicle rearmonitoring system of the invention;

FIG. 2 is a view of an example of a mounted state of a display of theinvention;

FIG. 3 is a flowchart illustrating an example of a main routine realizedby a processing unit of the invention;

FIG. 4A is a view showing a frame format of a cropped area of a rearenvironment image, when a traveling direction of a vehicle is forward;

FIG. 4B is a view showing a frame format of a cropped area of the rearenvironment image, when the traveling direction of the vehicle isbackward;

FIG. 5A is a view showing a frame format of a cropped area of a rearenvironment image as viewed from above the vehicle;

FIG. 5B is a view showing a frame format of a cropped area of a rearenvironment image as viewed from the side of the vehicle;

FIG. 6A is a view of an example of a vehicle rear image displayed on thedisplay when the traveling direction of the vehicle is forward; and

FIG. 6B is a view of an example of a vehicle rear image displayed on thedisplay when the traveling direction of the vehicle is backward.

DETAILED DESCRIPTION OF EMBODIMENTS

Hereinafter, example embodiments of the invention will be described withreference to the accompanying drawings.

FIG. 1 is a view of an example of the basic structure of a vehicle rearmonitoring system 1. This vehicle rear monitoring system 1 is mounted ina vehicle. The vehicle rear monitoring system 1 includes a processingunit 10.

The processing unit 10 may be formed by a computing and processing unitthat includes a CPU. The functions of the processing unit 10 may berealized by hardware, software, or a combination thereof as appropriate.For example, a suitable portion or all of the functions of theprocessing unit 10 may be realized by an ASIC (Application-SpecificIntegrated Circuit), an FPGA (Field Programmable Gate Array), or a DSP(Digital Signal Processor). Also, the processing unit 10 may be realizedby a plurality of processing units.

A display 20 is connected to the processing unit 10. The connectionbetween the processing unit 10 and the display 20 may be a wireconnection or a wireless connection, and may be a direct connection oran indirect connection via other equipment. Also, a portion or all ofthe functions of the processing unit 10 may be realized by a processingunit, not shown, inside the display 20.

The display 20 may be a suitable display device such as an LCD (LiquidCrystal Display) or HUD (Heads Up Display). The display 20 is arrangedis a suitable position inside the vehicle cabin (such as the upper sideof a center portion of an instrument panel). The display 20 ispreferably a large display, and may be a large display that forms theentire instrument panel.

A rear camera 40 is connected to the processing unit 10. The connectionbetween the processing unit 10 and the rear camera 40 may be a wireconnection or a wireless connection, and may be a direct connection oran indirect connection via other equipment. Also, a portion or all ofthe functions of the processing unit 10 may be realized by a processingunit, not shown, inside the rear camera 40.

The rear camera 40 captures an image of scenery to the rear of thevehicle by an imaging element such as a CCD (Charge-Coupled Device) or aCMOS (Complementary Metal-oxide Semiconductor), and obtains a rearenvironment image.

The rear camera 40 may be a camera capable to obtaining a visible colorimage, for example. The rear camera 40 may be a wide angle camera thatobtains a rear environment image of a relatively wide area. Also, therear camera 40 may be a cost-effective single focus type camera (i.e., acamera without a zoom function, in which the focal length is fixed), butit may also have a zoom function. The rear camera 40 may also be adedicated camera, or it may be a camera that is used for other purposes(such as for parking assist control, for example). The rear camera 40may obtain a rear environment image in real time while the vehicle istraveling, and supply this rear environment image to the processing unit10 in a stream format of a predetermined frame period. The rearenvironment image may also be supplied to the processing unit 10 afterundergoing predetermined processing (such as distortion correction orcoordinate transformation processing, for example).

A reverse shift switch 50 is connected to the processing unit 10. Thisreverse shift switch 50 outputs an ON signal to the processing unit 10when a transmission lever (i.e., a shift lever) is operated to a reverseposition, and is kept off when the transmission lever is in any otherposition.

FIG. 2 is a view of an example of the mounted state of the display 20.

In FIG. 2, the display 20 is provided in a center portion of theinstrument panel. The display 20 has a display area 22, as shown in FIG.2. A first display area 22A is included in a portion of this displayarea 22. The first display area 22A is an area that is smaller than thedisplay area 22. The first display area 22A may have a horizontally longouter shape that corresponds to an inner rearview mirror, for example.The first display area 22A may be set in a center portion of the displayarea 22. In the example shown in FIG. 2, the first display area 22A isset on an upper side of the center portion of the display area 22.Therefore, a display area 22B excluding the first display area 22A ofthe display area 22 is U-shaped. Also, in the example shown in FIG. 2,the positional arrangement of the first display area 22A issubstantially similar to that of the display area 22. The size of thefirst display area 22A of the display area 22, and position in which thefirst display area 22A is set and the like are arbitrary. Hereinafter,the entire display area 22 will be referred to as a “second display area22”).

FIG. 3 is a flowchart illustrating an example of a main routine realizedby the processing unit 10. With a configuration in which the vehiclerear image based on an image from the rear camera 40 is constantlydisplayed on the display 20, the routine shown in FIG. 3 may berepeatedly executed in predetermined cycles while an ignition switch ofthe vehicle is on, for example. With a configuration in which thevehicle rear image based on an image from the rear camera 40 isdisplayed on the display 20 under a predetermined condition (such asonly when the driver turns on the function, for example), the routineshown in FIG. 3 may be repeatedly executed in predetermined cycles whilethe function is on.

In step S300, it is determined whether the reverse shift switch 50 hasbeen turned on. That is, it is determined whether the shift lever hasbeen shifted to the reverse position. If the reverse shift switch 50 hasbeen turned on, the process proceeds on to step S306. If the reverseshift switch 50 has not been turned on (i.e., if the shift lever is inanother shift position such as a D-range), the process proceeds on tostep S302. In this way, when the traveling direction of the vehicle isforward, the process proceeds on to step S302, and when the travelingdirection of the vehicle is backward, the process proceeds on to stepS306. Here, the traveling direction of the vehicle is determined basedsolely on the position of the shift lever. Therefore, even if thevehicle speed is zero (i.e., even if the vehicle is stopped), if theshift lever is in the reverse position, it will be determined that thetraveling direction is backward, and if the shift lever is in anyposition other than the reverse position, it will be determined that thetraveling direction is forward. Also, the configuration may also be suchthat an image is not displayed when the shift lever is in the neutraland parking ranges.

In step S302, a vehicle rear image is created by cropping a portion ofarea (a first area) of the latest rear environment image input from therear camera 40. That is, a vehicle rear image is created by trimming thelatest rear environment image input from the rear camera 40 so that onlythe first area of that image remains. The first area may be a sizecorresponding to the first display area 22A.

In step S304, the vehicle rear image created in step S302 above isoutput to the first display area 22A of the display 20. At this time,the vehicle rear image may be enlarged or reduced by a predeterminedscale factor to match the first display area 22A of the display 20.Different information (such as a map screen of a navigation system, forexample) may also be displayed in the display area 22B other than thefirst display area 22A of the display 20. Also, the display area 22Bother than the first display area 22A of the display 20 may be in adisplay state in which a degree of driver distraction is relatively low,such as a solid dark color such as black (i.e., a low brightness stateor off). As a result, the light emitting area of the display 20 can bereduced, and the driver can be prevented from being blinded by, forexample, the movement of light (a high-intensity image) in the displayarea 22B, particularly at night or the like.

In step S306, a vehicle rear image is created by cropping a portion ofarea (a second area) of the latest rear environment image input from therear camera 40. That is, a vehicle rear image is created by trimming thelatest rear environment image input from the rear camera 40 so that onlythe second area of that image remains. The second area may be a sizecorresponding to the second display area 22. The size of the second areais larger than the size of the first area used in step S302. Therefore,with respect to the original image (i.e., the rear environment image),the cropped area of the vehicle rear image created in step S306 islarger than the cropped area of the vehicle rear image created in stepS302, and the size of the vehicle rear image created in step S306 isthat much bigger.

In step S308, the vehicle rear image created in step S306 is output tothe second display area 22 of the display 20. At this time, the vehiclerear image may be enlarged or reduced by a predetermined scale factor tomatch the second display area 22 of the display 20. However, in thiscase, the predetermined scale factor may be the same as thepredetermined scale factor used in step S304. As a result, theperspective of the vehicle rear image output to the second display area22 and the vehicle rear image output to the first display area 22A canbe kept the same.

In this way, according to the routine illustrated in FIG. 3, when thetraveling direction is forward, the vehicle rear image is displayed inthe first display area 22A of the, display 20. The first display area22A of the display 20 is smaller than the total display area (the seconddisplay area 22 in this example) of the display 20 as described above.Therefore, the degree of driver distraction caused by a relativelylarge-sized vehicle rear image being displayed in the forward field ofview when the traveling direction is forward is able to be appropriatelyreduced. Also, when displaying the vehicle rear image of the same visualrange as the inner rearview mirror in the first display area 22A, thedriver is able to use the display of the first display area 22A in thesame way as the inner rearview mirror. Therefore, in this case, thedriver is able to ultimately check the situation to the rear even if theinner rearview mirror is omitted. However, the inner rearview mirror mayalso be retained and used in combination with the display of the firstdisplay area 22A. On the other hand, according to the routineillustrated in FIG. 3, when the traveling direction is backward, thevehicle rear image is displayed in the second display area 22 of thedisplay 20. The second display area 22 of the display 20 issignificantly larger than the first display area 22A (in this example,the second display area 22 of the display 20 is the same as the entiredisplay area of the display 20). Accordingly, when the travelingdirection is backward, a large-sized vehicle rear image will bedisplayed, so visibility is good and useful information can be providedto the driver.

FIGS. 4A and 4B are views showing the processes in steps S302 and S306in FIG. 3, and are views showing frame formats of a cropped area of arear environment image (i.e., an extracted area of the vehicle rearimage).

In FIG. 4A, an example of an area of the vehicle rear image extractedfrom a rear environment image 70 when traveling forward (i.e., in stepS302) is denoted by reference character 72. In the example shown in FIG.4A, the cropped area is set above a center portion of the rearenvironment image 70 and corresponds to the area of the first displayarea 22A shown in FIG. 2. In this way, the vehicle rear image whentraveling forward may be created by trimming an area other than an area72 of the rear environment image 70.

In FIG. 4B, an example of an area of the vehicle rear image extractedfrom the rear environment image 70 when traveling backward (i.e., instep S306) is denoted by reference character 74. In the example shown inFIG. 4B, the cropped area is set to the entire rear environment image 70and corresponds to the area of the second display area 22 shown in FIG.2. Therefore, in this example, trimming is not performed. In this way,the vehicle rear image when traveling backward may be created using therear environment image essentially as it is.

FIGS. 5A and 5B are views showing the processes in steps S302 and S306in FIG. 3, and are views showing frame formats of a cropped area of arear environment image (i.e., an extracted area of the vehicle rearimage) from the viewpoint of the angle of view of the camera. FIG. 5A isview from above the vehicle, and FIG. 5B is a view from the side of thevehicle.

As shown in FIGS. 5A and 5B, the angle of view when the travelingdirection is forward (i.e., in step S302) is set narrower than the angleof view when the traveling direction is backward (i.e., step S306). Morespecifically, when viewed from above, as shown in FIG. 5A, the angle ofview when traveling forward is set to be within a first predeterminedangle left and right about a vehicle longitudinal central axis, whilethe angle of view when traveling backward is set to be within a secondpredetermined angle (>the first predetermined angle) left and rightabout the vehicle longitudinal central axis. The first predeterminedangle may be set such that the vehicle rear image of a visual rangecorresponding to the visual range of the inner rearview mirror is ableto be obtained, for example. The second predetermined angle may be setsuch that a vehicle rear image of a visual range that exceeds the visualrange of the inner rearview mirror is able to be obtained, for example.For example, the second predetermined angle may be a value within arange of 80° to 90°, inclusive. Also, when viewed from the side, asshown in FIG. 5B, the angle of view when traveling forward is set to bewithin a third predetermined angle downward from an uppermost directionthat is slightly upward from a horizontal plane, while the angle of viewwhen traveling backward is set to be within a fourth predetermined angle(>the third predetermined angle) downward from the uppermost direction.The third predetermined angle may be set such that a vehicle rear imageof a visual range corresponding to the visual range of the innerrearview mirror is able to be obtained, for example. The fourthpredetermined angle may be set such that a road situation in thevicinity of 0 meters behind the vehicle (i.e., the situation immediatelyto the rear of the vehicle) is able to be captured. For example, thefourth predetermined angle may be set to a value within a range of 80°to 90°, inclusive.

FIGS. 5A and 5B show the areas of the vehicle rear image when thetraveling direction of the vehicle is forward and when the travelingdirection of the vehicle is backward, from the viewpoint of the angle ofview of the camera. However, in actuality, the angle of view of the rearcamera 40 is not changed. That is, an angle of view of the rear camera40 such as that shown in FIGS. 5A and 5B is realized by varying thecropped area from the rear environment image (i.e., the extracted areaof the vehicle rear image) as described above with reference to FIG. 4and the like.

As is evident from FIGS. 5A and 5B, according to this exampleembodiment, when traveling forward, information within a relativelynarrow angle of view is displayed on the display 20, so the degree ofdriver distraction from a large amount of information that includesunnecessary information when traveling forward is able to beappropriately reduced. On the other hand, when traveling backward, avehicle rear image of a wide angle of view is displayed on the display20, so useful information is able to be provided to the driver whoshould be paying attention to a wide area to the rear of the vehicle.For example, an obstacle or an object requiring attention (i.e., anobject that the driver needs to be careful of) that is unable to becaptured in the angle of view when traveling forward is able to bewithin the angle of view when traveling backward, so blind spots areable to be minimized.

FIG. 6A is a view of an example of a vehicle rear image displayed on thedisplay 20 when the traveling direction of the vehicle is forward. FIG.6B is a view of an example of a vehicle rear image displayed on thedisplay 20 when the traveling direction of the vehicle is backward.

When the traveling direction of the vehicle is forward, the vehicle rearimage is displayed in the first display area 22A of the display 20, asshown in FIG. 6A. In the example shown in FIG. 6A, an image of anothervehicle A parked on the side of the road behind the vehicle is includedin the vehicle rear image. If the driver shifts the shift lever into thereverse position from this state, the vehicle rear image will bedisplayed with the display area of the display 20 enlarged from thefirst display area 22A to the second display area 22. At this time, asshown in FIGS. 6A and 6B, an outer frame (outer shape) 80 of the vehiclerear image is enlarged to match the enlargement of the cropped area,while the focal length of the rear camera 40 is kept the same. In thisway, a switch is able to be realized while keeping the focal length ofthe rear camera 40 the same. Therefore, the vehicle rear image that isdisplayed in the first display area 22A right before the switch isincluded in the vehicle rear image displayed in the second display area22 at essentially the same size and positional relationship. Forexample, the image of the other vehicle A (the parked vehicle) includedin the vehicle rear image displayed in the first display area 22A rightbefore the switch is present in the vehicle rear image displayed in thesecond display area 22 at the same size and positional relationship. Asa result, the driver is able to instinctively understand therelationship between the vehicle rear image displayed in the firstdisplay area 22A and the vehicle rear image displayed in the seconddisplay area 22 currently switched to, and is therefore able to quicklyobtain the necessary information from the vehicle rear image displayedin the second display area 22. That is, when the two switch, objects inthe visible range do not change, so the same perspective is able to bemaintained. As a result, the driver is able to easily and appropriatelydetermine the area where objects to the rear within the new field ofvision (such as another vehicle B in FIG. 6B) are.

Also, when this switch is made, the outer frame 80 of the vehicle rearimage may be continuously changed by animation display. That is, theouter frame 80 is enlarged in a stepped manner from the size shown inFIG. 6A to the size shown in FIG. 6B. In conjunction with this, thecropped area for the vehicle rear image may also be continuouslyenlarged. As a result, the driver is able to instinctively understandthe relationship between the vehicle rear image displayed in the firstdisplay area 22A and the vehicle rear image displayed in the seconddisplay area 22 currently switched to, and is therefore able to quicklyobtain the necessary information from the vehicle rear image displayedin the second display area 22. However, the switch from the vehicle rearimage shown in FIG. 6A to the vehicle rear image shown in FIG. 6B mayalso be made in a discontinuous manner (i.e., instantly), without usingthe animation display.

Also, conversely, if the driver shifts the shift lever from the reverseposition to another position, the vehicle rear image will be displayedwith the display area of the display 20 reduced from the second displayarea 22 (i.e., from the state shown in FIG. 6B) to the first displayarea 22A, as shown in FIG. 6A. At this time, similarly, the outer frame(i.e., the outer shape) 80 of the vehicle rear image is reduced to matchthe reduction of the cropped area, while the focal length of the rearcamera 40 is kept the same, as shown in FIGS. 6A and 6B. Also, when thisswitch is made, the outer frame 80 of the vehicle rear image may becontinuously changed by animation display. That is, the outer frame 80may be reduced in a stepped manner from the size shown in FIG. 6B to thesize shown in FIG. 6A. However, the switch from the vehicle rear imageshown in FIG. 6A to the vehicle rear image shown in FIG. 6B may also bemade in a discontinuous manner (i.e., instantly), without using theanimation display.

In this example embodiment, when the outer frame 80 of the vehicle rearimage is enlarged or reduced, only the cropped area is enlarged orreduced as described above, i.e., the vehicle rear image is not enlargedor reduced to match the enlargement or reduction of the outer frame 80.However, the focal length does not necessarily have to be kept the sameas long as the driver is able to understand the relationship between thevehicle rear image displayed in the first display area 22A and thevehicle rear image displayed in the second display area 22 by followingthe animation display that enlarges or reduces the outer frame 80 asdescribed above, for example. When a switch is made from the vehiclerear image shown in FIG. 6A to the vehicle rear image shown in FIG. 6B,for example, animation display that enlarges the outer frame 80 may beperformed, and the focal length may be continuously (gradually) reduced(the zoom factor may be gradually increased). However, in this case aswell, the difference in the cropped area from the rear environment imagewhen traveling forward compared with when traveling backward may be ableto be maintained (i.e., the cropped area when traveling backward may beset larger than the cropped area when traveling forward). With thismodified example, there is a possibility that the processing load andcost may change by the amount of the required processing to vary thefocal length (or this function). Also, the focal length changes beforeand after the switch, so the perspective of the display will changebefore and after the switch.

While various example embodiments of the invention have been described,the invention is not intended to be limited to these exampleembodiments. That is, various modifications and substitutions may bemade to the example embodiments described above without departing fromthe scope of the invention.

For example, in the example embodiment described above, the seconddisplay area 22 corresponds to the entire display area of the display20, but it may also be only a portion of the entire display area of thedisplay 20 as long as it is larger than the first display area 22A.Also, in the example embodiment described above, the vehicle rear imagedisplayed in the second display area 22 is directly created from therear environment image (i.e., created without trimming), but it may alsobe created by cropping a portion of the rear environment image as longas it includes, and is wider than, the cropped area for creating thevehicle rear image displayed in the first display area 22A.

Also in the example embodiment described above, the cropped area forcreating the vehicle rear image displayed in the first display area 22Ais fixed, but it may also be variable. Similarly, the cropped area forcreating the vehicle rear image displayed in the second display area 22is fixed, but it may also be variable.

While the invention has been described with reference to exampleembodiments thereof, it is to be understood that the invention is notlimited to the described embodiments or constructions. To the contrary,the invention is intended to cover various modifications and equivalentarrangements. In addition, while the various elements of the exampleembodiments are shown in various combinations and configurations, othercombinations and configurations, including more, less or only a singleelement, are also within the scope of the invention.

1.-8. (canceled)
 9. A vehicle rear monitoring system comprising: acamera that captures an image of an area to a rear of a vehicle andoutputs the captured image; a processing unit that processes thecaptured image, and creates a vehicle rear image; a display device thatdisplays the vehicle rear image; and a traveling direction detectingdevice that detects a traveling direction of the vehicle and notifiesthe processing unit of the detected traveling direction, wherein theprocessing unit creates a first vehicle rear image that is the vehiclerear image that is displayed in a first display area that is a portionof a display area of the display device, when the traveling direction isforward, and creates a second vehicle rear image that is the vehiclerear image that is displayed in a second display area that is within thedisplay area of the display device and that is an area that includes thefirst display area and is larger than the first display area, when thetraveling direction is backward.
 10. The vehicle rear monitoring systemaccording to claim 9, wherein the processing unit creates the vehiclerear image by cropping the captured image, and a cropped area when thetraveling direction is backward is larger than the cropped area when thetraveling direction is forward.
 11. The vehicle rear monitoring systemaccording to claim 9, wherein the second vehicle rear image is an imagecaptured at the same focal length as the first vehicle rear image. 12.The vehicle rear monitoring system according to claim 9, wherein theprocessing unit continuously changes an outer frame of a display area ofthe vehicle rear image by animation display when a change in thetraveling direction is detected.
 13. The vehicle rear monitoring systemaccording to claim 12, wherein the traveling direction detecting deviceis a shift lever, and detects a change in the traveling directionaccording to whether the shift lever has been shifted into reverse. 14.The vehicle rear monitoring system according to claim 9, wherein thesecond display area is the entire display area of the display device.15. The vehicle rear monitoring system according to claim 9, wherein theprocessing unit places an area except for the first display area of thesecond display area in a display state of a solid dark color when thetraveling direction is forward.
 16. The vehicle rear monitoring systemaccording to claim 9, wherein the processing unit creates the vehiclerear image such that an object included in the first vehicle rear imageand the second vehicle rear image is the same size and in the samepositional relationship when a change in the traveling direction of thevehicle is detected.